Rotor support for an electrical machine

ABSTRACT

A rotor carrier for a rotor of an electric machine and to a hybrid module with such a rotor carrier. The rotor carrier includes a pot-shaped base body. The base body overlaps only a portion of the axial extension of the rotor, in that the rotor carrier comprises a second supporting body that has elements on an outer circumferential surface for a positive engagement connection and/or frictional engagement connection between supporting body and rotor, in that the supporting body has a radially extending flange, and in that the bottom of the base body and the flange of the supporting body are connected to one another.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a U.S. national stage of Application No. PCT/EP2019/068255 filedJul. 8, 2019. Priority is claimed on German Application No. DE 10 2018211 376.9 filed Jul. 10, 2018 the content of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention is directed to a rotor carrier for an electric machine,particularly in a hybrid powertrain of a vehicle.

2. Description of Related Art

Besides solid rotors, annular rotors which are arranged around an axisof rotation are known in the prior art in electric machines. It isknown, for example, from DE 10 2013 221 643 A1 that a lamination stackof a rotor is received on an outer plate carrier and connected to therotational axis.

SUMMARY OF THE INVENTION

It is the object of one aspect of the invention to provide analternative to the prior art which has a better support of the rotor,makes optimal use of installation space and is also simple andeconomical to produce.

According to one aspect of the invention, a rotor carrier for a rotor ofan electric machine comprises a pot-shaped base body, the base body hasan engagement element on an outer circumferential surface facing therotor which make possible a positive engagement connection and/orfrictional engagement connection between the base body and rotor,receptacles for parts of a clutch are provided on an innercircumferential surface remote of the rotor over a portion of the axialextension, and the base body is connected to a hub by a radiallyextending bottom. The invention is characterized in that the base bodyoverlaps only a portion of the axial extension of the rotor, in that therotor carrier comprises a second supporting body which likewise hasengagement elements on an outer circumferential surface which makepossible a positive engagement connection and/or frictional engagementconnection between supporting body and rotor, in that the supportingbody has a radially extending flange, and in that the bottom of the basebody and the flange of the supporting body are connected to one another.

A profiling, for example, is provided at the base body for theconnection between the base body and the rotor with which projectionsand/or recesses are provided at least on the outer circumferentialsurface, which projections and/or recesses cooperate with correspondingmating pieces on the inner surface of the rotor in order to produce apositive engagement connection. Alternatively or cumulatively,projections or recesses such as steps or annular grooves can also beprovided in circumferential direction and are usable for a positiveengagement connection or frictional engagement connection. A frictionalengagement connection in which the rotor is connected to the base bodyvia clamping elements, screws, rivets, or the like can also be providedinstead of a positive engagement connection. Material bond connectionsin which the rotor is welded to the base body are also possible inprinciple. Combinations in which different types of connections areused, for example, to form or secure connections in differentdirections, are also possible.

The base body is connected to a hub by a radially extending bottom inorder to be able to transmit a torque. In this context, the term “hub”means and comprehends not only a conventional hub mounted on a shaft butalso a direct connection to a shaft or also the connection to acomponent part downstream in the powertrain, for example, a converterhousing.

The bottom is preferably integral with the base body so that the basebody has a pot-like shape. Embodiment forms in which the bottom ismanufactured separately and is fixedly connected to the base body, forexample, by welding, are also possible.

Receptacles for parts of a clutch are provided at the innercircumferential surface of the axial portion of the base body. Theseparts are preferably grooves or projections in axial direction whichserve to receive plates of a multiple-plate clutch. Accordingly, thebase body is simultaneously the outer plate carrier of a clutch. Theclutch can interrupt a power flow from or to an internal combustionengine located upstream in the powertrain, for example.

The base body only extends over a portion of the axial extension of therotor, and the base body can protrude over the rotor in axial direction.The radially extending bottom is preferably provided at an axial end ofthe base body. The bottom is preferably arranged inside of the rotor inaxial direction so that an advantageous power flow can be achieved.

To support the rotor over the entire axial length, the rotor carrier hasa supporting body which is formed as a separate component part, and therotor carrier is accordingly constructed from two parts.

On an outer circumferential surface, the supporting body likewise hasengagement elements that provide a positive engagement connection and/orfrictional engagement connection between supporting body and rotor.These engagement elements are preferably constructed analogous to theabove-described means at the base body.

The supporting body further comprises a radially extending flange forconnecting the supporting body to the bottom of the base body so thatthe base body and the supporting body are fixedly arranged relative toone another and a rotor carrier is formed for the rotor. The connectionbetween base body and supporting body is preferably carried out byriveting, screwing or welding, although other types of connections arepossible. The two-part construction of the rotor carrier simplifies thegeometry of the individual component parts, and it is possible at thesame time to use the individual component parts possibly also in othervariants of a hybrid module owing to a modular construction.

Embodiment forms of a rotor carrier are characterized in that thesupporting body has, as separate component part, a flange which isformed shorter or longer in radial direction than the bottom of the basebody. The rotor carrier is connected to a hub. For this connection, thebottom or the flange preferably extends through to the hub or isconnected to a converter housing which is fixedly connected to the hub.In addition to an identical radial length of bottom and flange in whichboth of the latter are connected to the hub, it is preferred that onlythe bottom of the base body or the flange of the supporting body extendsthrough to the hub, since material and axial installation space canpossibly be saved at the hub in this way.

Rotor carriers according to further embodiment forms are characterizedin that a converter housing is formed as supporting body. Instead of aseparate component part as supporting body, the converter housing can beformed as supporting body at its end facing the clutch. In this case,the elements for receiving the rotor are correspondingly formed on acircumferential surface of the converter housing which has a diameteridentical to that of the base body. In these embodiment forms, theflange of the supporting body is correspondingly provided at the axialend of the converter housing, and the bottom of the base body isdirectly connected to the converter housing and to the flange at theconverter housing, respectively. In this way, the quantity of componentparts can be reduced and installation space can be saved. Further, thesupporting body as component part of the converter housing has a highstiffness.

Embodiment forms of a rotor carrier are characterized in that the basebody has a different thickness than the supporting body. Depending onthe occurring loads and the amount of axial support of the rotor, thebase body and the supporting body can be constructed with differentthicknesses. Compared to a rotor carrier which extends in one part overthe axial length, material and, therefore, weight and costs can be savedby the different thicknesses because of the adaptation to the load.

Rotor carriers according to embodiment forms are characterized in thatthe base body and the supporting body are connected to one another byriveting. Using riveting, the component parts can be securely connectedto one another simply and quickly without introducing large amounts ofheat.

Rotor carriers according to embodiment forms are characterized in thatthe base body and the supporting body are connected to one another bywelding. By welding, the component parts can be connected to one anothersimply and securely without having to use additional component partssuch as screws or rivets.

Embodiment forms of a rotor carrier are characterized in that the basebody has a larger axial overlap with the rotor than the supporting body.In principle, the division between base body and supporting body inaxial direction can be selected as desired. However, with respect to therequired installation space, it is advantageous when the base bodyoverlaps a larger proportion of the rotor in axial direction because thebase body simultaneously surrounds parts of the clutch.

In embodiment forms, rotor carriers are characterized in that the basebody and/or the supporting body are formed longer than the rotor atleast at one axial end. Because of the axial overlap, an at leastpartial mechanical protection is afforded for the ends of the rotor.Further, the possibility for mounting retaining elements such asretaining rings and the like is provided at the axial overlap. Theprotruding rotor carrier can also be used in particular for balancingthe rotor by fixing balancing weights to the protruding rotor carrier orby local removal of material.

Rotor carriers according to embodiment forms are characterized in thatthe base body and/or the supporting body has at least one cutout whichis continuous in radial direction for the passage of oil. At least onecutout is provided in order to guide oil from the inner side to theouter side for lubrication and cooling. This cutout is preferablyarranged in the area of an axial end of the lamination stack of therotor or so as to lead into an oil channel formed between the rotorcarrier and the lamination stack.

Rotor carriers according to preferred embodiment forms are characterizedin that the cutout is arranged in the bottom area of a groove providedat the inner circumferential surface. In addition to the cutouts,guiding elements can be provided at the supporting body or base body inorder to guide oil impinging from the inside to the cutouts or toselectively deliver oil outward. These guiding elements can beconstructed as channels, annular grooves or recesses, preferably so asto be inclined toward the cutout. Alternatively, raised guiding elementsare also possible as struts, projections or steps. These guidingelements can possibly serve at the same time as receptacles for theparts of a clutch.

Preferred embodiment forms of a rotor carrier are characterized in thata plurality of cutouts are arranged so as to be distributed over thecircumference. For a more uniform distribution of the oil and in orderto prevent unbalance, a plurality of cutouts are distributed, preferablysymmetrically, over the circumference. In this regard, a plurality ofcutouts can also be provided at different axial positions so that thecooling can be improved on both sides, for example.

A further aspect of the invention is a hybrid module comprising an inputshaft, a clutch, an electric machine, a torque converter and an outputshaft, which is characterized in that a rotor carrier is providedaccording to one of the embodiment forms described above. Accordingly,the above-described advantages with respect to axial installation spaceand the like can be utilized in a hybrid module.

The embodiment forms are not limited to the examples given above and maybe achieved through further corresponding constructions. The features ofthe embodiment forms may be combined in any desired manner.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be described in more detail in the followingreferring to drawings. Like or similar elements are designated byconsistent reference numerals. The drawings show:

FIG. 1 is a schematic section of a hybrid module;

FIG. 2 is a rotor carrier;

FIG. 2A is a rotor carrier:

FIG. 3 is a detail of an embodiment example; and

FIG. 3A is a detail of an embodiment example.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIG. 1 shows a hybrid module according to an embodiment example in aschematic sectional view, one half of which has been omitted in view ofsymmetry. The hybrid module comprises a housing 1 within which isarranged an electric machine 2 with a stator 2.1, which is fixed withrespect to rotation relative to the housing 1, and a rotatable rotor2.2.

The hybrid module has a torque converter 5. The converter housing 5.1 isconnected to a hub 4. An impeller 5.3 of the torque converter 5 isfixedly connected to a converter housing 5.1 of the torque converter 5.A stator wheel 5.4 of the torque converter 5 is supported so as to befixed with respect to relative rotation in one rotational direction viaa freewheel. A turbine wheel 5.5 of the torque converter 5 is connectedto a turbine shaft 5.2 of the torque converter 5. The hybrid modulefurther has an additional, optional torsional vibration mass damper 10which is arranged within and on the converter housing 5.1. The turbineshaft 5.2 is connected to an output shaft 6 of an automatictransmission, not shown in more detail. Further, a lockup clutch 11 isarranged inside of the converter housing 5.1. The converter housing 5.1is directly connectable to the turbine shaft 5.2 by engaging the lockupclutch 11.

The hub 4 is formed as a hollow shaft which is arranged coaxial to theoutput shaft 6 and so as to enclose the latter. In the depicted example,the input shaft 3 is likewise constructed as a hollow shaft and isarranged coaxial to the hub 4. A plurality of bearings 12 are arrangedbetween the output shaft 6 and the hub 4, between the hub 4 and theinput shaft 3 and between the input shaft 3 and the housing 1 andsupport the component parts relative to one another. The hub 4 isconnected on its outer side to the converter housing 5.1 and to one sideof the clutch 7.

A vibration damper 8, which is connected to an internal combustionengine, not shown, is provided on the input shaft 3. Possible torsionalvibrations are reduced by the vibration damper 8 in order to supply thehybrid module with a torque or rotational movement that is as uniform aspossible. At the same time, positional tolerances and alignmenttolerances between the internal combustion engine and the hybrid modulecan be compensated by the vibration damper 8.

The housing 1 separates a wet space of the hybrid module from a dryspace. The wet space is sealed relative to the dry space by a seal 9,which is arranged preferably directly adjacent to a bearing 12.

A clutch 7 by which the internal combustion engine can be disconnectedfrom the rest of the powertrain is also provided inside the housing 1.To this end, the clutch 7 is arranged in the power flow between theinput shaft 3 and the hub 4. More precisely, the parts of the clutch 7are correspondingly connected to the input shaft 3 and to a rotorcarrier. In the depicted embodiment example, the clutch 7 is constructedas a multiple-plate clutch.

The rotor 2.2 of the electric machine 2 is connected to a rotor carrier.In the depicted embodiment example, the rotor carrier is formed by abase body 13 and a supporting body 14, each of which has a pot-likebasic shape and supports part of the axial length of the rotor 2.2. Thebase body 13 and the supporting body 14 have an annular outer contourwith an identical outer diameter, the rotor 2.2 being mounted on theouter circumferential surface thereof. The base body 13 in this instancehas a larger axial length than the supporting body 14 and,correspondingly, approximately two thirds of the rotor 2.2 are supportedby the base body 13 and one third of the rotor 2.2 supported by thesupporting body 14. The area of the rotor 2.2 supported by the base body13 is preferably in the range of from 25% to 75% of the axial length ofthe rotor 2.2 so that the bottom of the base body 13 is arranged in thecentral area of the rotor 2.2.

The radially extending bottom of the base body 13 and the flange of thesupporting body 14 face one another and are connected to one another. Aconnection to the hub 4 is carried out via the bottom of the base body13. Both the base body 13 and the supporting body 14 protrude in axialdirection relative to the rotor 2.2; in other words, together they havea larger axial length than the rotor 2.2.

In order to secure the axial position of the rotor 2.2 on the base body13, a retaining element 15 is provided in a groove. The retainingelement 15 can be constructed such that it is at least partially elasticin order to compensate for manufacturing tolerances and the like. Anaxial retention is also provided on the opposite side of the rotor 2.2by a corresponding retaining element 15. Instead of a retaining element15, one or more projections, steps or the like can also be provided atleast on one side. Alternatively, the axially protruding area of thebase body 13 or of the supporting body 14 can also be reformed radiallyoutward so as to form a collar for axial limiting.

In the depicted embodiment example, the supporting body 14 is formedwith a wall thickness which is thinner than that of the base body 13 sothat material as well as weight are saved. In principle, the twocomponent parts of the rotor carrier can also be constructed with anidentical wall thickness.

By corresponding cutouts or balancing elements, not shown, the axiallyprotruding areas can also be utilized for guiding oil for lubricatingand cooling the electric machine 2 or for balancing the electric machine2.

An axial portion of the base body 13 is provided with a profiling inorder to form projections and recesses in the manner of a spline whichare distributed over the circumference. These projections and recessesserve to receive parts of the clutch 7—the outer plates of the clutch 7in the depicted example—so that the base body 13 constitutes the outerplate carrier of the clutch 7.

In FIG. 1 , the flange of the supporting body 14 is constructed with asmaller radial extension than the bottom of the base body 13. The flangeis connected to the bottom of the base body 13 via rivets, not shown.Instead of rivets, the connection can also be carried out in particularby welding, screwing or clinching.

FIG. 2 and FIG. 2A show further embodiment example of a rotor carrier,FIG. 2A including cutouts 131. The basic construction is the same, andreference is made to the above description referring to FIG. 1 .

In contrast to the example from FIG. 1 , the area axially protrudingover the rotor 2.2 is reformed radially outward in the supporting body14 to form a step.

Further, tongues 16 are arranged at the supporting body 14 so as to bedistributed over the circumference in order to facilitate the alignmentand positioning of the base body 13 relative to the supporting body 14.Alternatively or additionally, an alignment groove 17 that extends overboth component parts can be used for this purpose and can also beutilized for positioning the rotor 2.2.

A subarea of a further embodiment example is shown in FIG. 3 . However,the supporting body 14 is formed integral with the converter housing 5.1or a portion of the converter housing 5.1 forms the supporting body 14.The base body 13 is connected directly to the converter housing 5.1 inthis case. As is shown, the connection of the bottom and the flange canbe carried out by welding or also by other connection methods which werementioned above or combinations thereof. As shown in FIG. 3A, thesupporting body 14 has a flange that is formed longer in radialdirection than the bottom of the pot-shaped base body 13.

As in FIG. 1 , recesses and projections are provided on the innercircumferential surface of the base body 13 as receptacle for parts ofthe clutch 7.

Projections and recesses, in this case in the form of axially extendinggrooves, are provided at the base body 13 and supporting body 14 forreceiving and fastening the rotor 2.2 on the outer circumferentialsurface.

Portions of the lockup clutch 11 are shown inside the converter housing5.1.

The invention is not limited to the embodiments described herein. As hasalready been stated, only individual advantageous features can also beprovided, or various features from different examples may be combinedwith one another.

Thus, while there have shown and described and pointed out fundamentalnovel features of the invention as applied to a preferred embodimentthereof, it will be understood that various omissions and substitutionsand changes in the form and details of the devices illustrated, and intheir operation, may be made by those skilled in the art withoutdeparting from the spirit of the invention. For example, it is expresslyintended that all combinations of those elements and/or method stepswhich perform substantially the same function in substantially the sameway to achieve the same results are within the scope of the invention.Moreover, it should be recognized that structures and/or elements and/ormethod steps shown and/or described in connection with any disclosedform or embodiment of the invention may be incorporated in any otherdisclosed or described or suggested form or embodiment as a generalmatter of design choice. It is the intention, therefore, to be limitedonly as indicated by the scope of the claims appended hereto.

The invention claimed is:
 1. A rotor carrier for a rotor of an electricmachine, comprising: a pot-shaped base body, having first engagementelements on an outer circumferential surface facing the rotor configuredfor a positive engagement connection and/or frictional engagementconnection between base body and rotor; an inner circumferential surfaceremote of the rotor defines receptacles for parts of a clutch over aportion of an axial extension of the inner circumferential surface; aradially extending bottom by which the pot-shaped base body is connectedto a hub; wherein the pot-shaped base body overlaps only a portion of anaxial extension of the rotor, wherein the rotor carrier comprises asecond supporting body having second engagement elements on an outercircumferential surface configured for a positive engagement connectionand/or frictional engagement connection between supporting body androtor, wherein the second supporting body has a radially extendingflange, and wherein the bottom of the pot-shaped base body and theradially extending flange of the supporting body are connected to oneanother.
 2. The rotor carrier according to claim 1, wherein thesupporting body has, as a separate component part, a flange that isformed shorter or longer in radial direction than the bottom of thepot-shaped base body.
 3. The rotor carrier according to claim 1, whereina converter housing is formed as supporting body.
 4. The rotor carrieraccording to claim 3, wherein the pot-shaped base body has a differentthickness than the supporting body.
 5. The rotor carrier according toclaim 1, wherein the pot-shaped base body and the supporting body areconnected to one another by riveting.
 6. The rotor carrier according toclaim 1, wherein the pot-shaped base body and the supporting body areconnected to one another by welding.
 7. The rotor carrier according toclaim 1, wherein the pot-shaped base body has a larger axial overlapwith the rotor than the supporting body.
 8. The rotor carrier accordingto claim 1, wherein the pot-shaped base body and/or the supporting bodyare formed longer than the rotor at least at one axial end.
 9. The rotorcarrier according to claim 1, wherein the pot-shaped base body and/orthe supporting body has at least one cutout which is continuous in aradial direction for a passage of oil.
 10. The rotor carrier accordingto claim 9, wherein the at least one cutout is arranged in a bottom areaof a groove provided at the inner circumferential surface.
 11. The rotorcarrier according to claim 9, wherein a plurality of cutouts arearranged so as to be distributed over a circumference.
 12. A hybridmodule comprising: an input shaft; a clutch; an electric machine; atorque converter; an output shaft; and a rotor carrier comprising: apot-shaped base body, having first engagement elements on an outercircumferential surface facing a rotor configured for a positiveengagement connection and/or frictional engagement connection betweenbase body and rotor; an inner circumferential surface remote of therotor defines receptacles for parts of the clutch over a portion of anaxial extension of the inner circumferential surface; a radiallyextending bottom by which the pot-shaped base body is connected to ahub; wherein the pot-shaped base body overlaps only a portion of anaxial extension of the rotor, wherein the rotor carrier comprises asecond supporting body having second engagement elements on an outercircumferential surface configured for a positive engagement connectionand/or frictional engagement connection between supporting body androtor, wherein the second supporting body has a radially extendingflange, and wherein the bottom of the pot-shaped base body and theradially extending flange of the supporting body are connected to oneanother.